Re: I bought a 1973 cobalt need to know everything i can never boated before!!!
A friend told be that BOAT stands for "Break Out Another Thousand".
If I were you, I would do the things that I knew how to do, and either seek advice from someone or have the local Cobalt dealer do the work. Since you put hole in the bottom, I would get that fixed by someone that was good with fiberglass, unless you are confident in doing that work. Don't need water coming in when you're out boating in the middle of a lake.
Your title says you are new to boating. I suggest taking a boating course to learn the basics. There is a online boating course at boatus.com. Your state's water patrol web site should have some time of boating course also.
And of course you can always ask your questions on the forums. Lots of knowledgable boat people here that can give great advice.
Good luck with your project and welcome to the Cobalt world.
Phil